pythongh-138659: Typo in the gc module docstring (python#138660)

docs(gc): fix typo in get_threshold() docstring

Removes a duplicate "the" from the docstring for the `gc.get_threshold()` function.

Author: axdeyy

Modules/gcmodule.c

@@ -478,7 +478,7 @@ PyDoc_STRVAR(gc__doc__,
 "set_debug() -- Set debugging flags.\n"
 "get_debug() -- Get debugging flags.\n"
 "set_threshold() -- Set the collection thresholds.\n"
-"get_threshold() -- Return the current the collection thresholds.\n"
+"get_threshold() -- Return the current collection thresholds.\n"
 "get_objects() -- Return a list of all objects tracked by the collector.\n"
 "is_tracked() -- Returns true if a given object is tracked.\n"
 "is_finalized() -- Returns true if a given object has been already finalized.\n"